1. GRB Theory and observations Useful reviews: Waxman astro-ph/0103186 Ghisellini astro-ph/0111584 Piran astro-ph/0405503 Meszaros astro-ph/0605208 Gehrels 2009 ariv:0909.1531 Useful links: http://qso.lanl.gov/~clf/papershttp://qso.lanl.gov/~clf/papers (Chris Fryer lectures)

2. GRBs most luminous objects in the Universe!! Sun Luminosity L  ~4  10 33 erg/s Supernova L~10 51 erg/s Galaxies with nuclei L~10 48 erg/s GRB luminosity L~10 52 erg/s

3. GRB light curves

4. GRBs: flashes of 0.1 MeV gamma rays that last 1-100 s Isotropy in the sky Duration: Duration: T 90  0.2 s short 20 s long Flux: f = 10 -4 -10 -7 erg/cm 2 s Flux: f = 10 -4 -10 -7 erg/cm 2 s Rate R  300/yr BATSE and 100/yr Swift Rate R  300/yr BATSE and 100/yr Swift  -ray observations summary Variability: Variability: Most show  t ~ 64 ms Some  t ~ 1 ms

5. GRB 3 July 1969: first detection of a GRB by Vela 5A

6. Vela Satellites 10 5 km Orbits Launched in pairs – launched 1963-1965 Operated until 1979 All satellites allowed for some localization.

7. First Detected Gamma-Ray Burst

8. Vela Satellites - Results 73 Bursts in Gamma-Rays over 10 years Not from the Earth (not weapons tests) and not in the plane of solar system Ray Klebasadel

9. Gamma-Ray Bursts in the Solar System Lightning in the Earth’s atmosphere (High Altitude) Relativistic Iron Dust Grains Magnetic Reconnection in the Heliopause Red Sprite Lightning

10. Gamma-Ray Bursts in the Milky Way Accretion Onto White Dwarfs Accretion onto neutron stars I) From binary companion II) Comets Neutron Star Quakes Magnetic Reconnection X-ray Novae

11. Galactic Gamma-Ray Bursts: Soft Gamma-Ray Repeaters One Class of GRBs Is definitely Galactic: Soft gamma-ray Repeaters (SGRs) Characteristics: 1)Repeat Flashes 2)Photon Energy Distribution lower Energy than other GRBs (hard x-rays) X-ray map of N49 SN remnant. The white Box shows location of the March 5 th event

13. Models for SGRs Accretion I) Binary Companion - no companion seen II) SN Fallback – Too long after explosion Magnetic Fields ~10 15 G Fields - “Magnetars”

14. Extragalactic Models Large distances means large energy requirement (10 51 erg) Event rate rare (10 - 6 -10 -5 per year in an L * galaxy) – Object can be exotic

15. Cosmological Models Collapsing WDs Stars Accreting on AGN White Holes Cosmic Strings Black Hole Accretion Disks I) Binary Mergers II) Collapsing Stars

16. Black-Hole Accretion Disk (BHAD) Models Binary merger or Collapse of rotating Star produces Rapidly accreting Disk (>0.1 solar Mass per second!) Around black hole.

17. Massive Star Collapse Collapsar Model – Collapse of a Rotating Massive Star into a Black Hole Stan Woosley Main Predictions: Beamed Explosion, Accompanying supernova-like explosion

18. BATSE - Burst And Transient Spectrometer Experiment BATSE Module BATSE Consists of two NaI(TI) Scintillation Detectors: Large Area Detector (LAD) For sensitivity and the Spectroscopy Detector (SD) for energy coverage 8 Detectors Almost Full Sky Coverage Few Degree Resolution 20-600keV

19. Galactic Models

20. BATSE Results – Isotropy Cosmological Models Favored!

21. Gamma-Ray Burst Lightcurves GRB Lightcurves have A broad range of Characteristics Fast Rise Exponential Decay “FREDs” GRB970508 GRB990316

22. Gamma-Ray Burst Durations Two Populations: Short – 0.03-3s Long – 3-1000s Possible third Population 1-10s

23. Gamma-Ray Burst Duration vs. Energy Spectrum

24. BATSE - Summary GRBs are Isotropic – The beginning of the end for Galactic Models, but persistent theorists move the Galactic Models to the Halo GRBs come in all shapes and sizes but two obvious subgroups exist - I) Short, Hard Bursts II) Long, Soft Bursts

25. BeppoSAX Italian-Dutch Satellite Launch: April 30, 1996 Goal: Positional Accuracy <5 arc minutes Honoring Giuseppe Occhialini

26. High Pressure Gas Scintillation Proportional Counter WFC – 40 o x 40 o, 2-28keV

27. BeppoSAX Instruments Xenon Gas Scintillator Energy Range:.1- 1keV (1-10keV) ~1 arc minute resolution Goal – Localize Object HPGSPC - High Pressure Xenon/He Gas PDS Phoswitch - NaI(Tl), CsI(Na) Scintillators 4-120keV (15-300keV) Goal – Broad Energy resolution in X-ray narrow field LECS/MECS HPGSPC PDS

28. BeppoSAX: I GRB sono sorgenti a distanze cosmologiche! Costa+ 1997 BeppoSAX Van Paradijs+ 1997 WHT Pedichini+ 1997 Campo imperatore

29. GRB 970228 – host galaxy observed? This blob, a peculiar Galaxy to be sure, Is in the same position As the Burst! Could it have been the GRBs host? The galaxy has a Redshift of 0.695.

30. GRB 970508 – Optical Counterpart BeppoSAX X-ray Localization Allowed a The Optical Transient to Be detected While still on The rise. OT allowed Spectral Measurement!

31. GRB970508 – Absorption Lines: z=0.835 Fe II Mg II Mg II I Optical Emission Absorption Metzger et al. 1997 flux Wavelength flux

32. Host Galaxy Detected for GRB970508 Z=0.835 Wavelength flux

33. Radio Twinkling can also be used to estimate the GRB distance: consistent with z=0.835 Just as the Earth’s Atmosphere Causes light To scatter Causing point Sources to “twinkle”, the Interstellar Medium causes Radio emission To twinkle. When The burst gets Large enough, Like planets, the Twinkling stops.

34. ISM Scattering T=0, point Source Twinkle, Twinkle Observer Always Sees Part of Burst T=t, r=c t Where c is speed of light Waxman, Kulkarni, & Frail 1997

35. A crash Course in Scintillations Scintillations determine the size of the source in a model independent way. The size (~10 17 cm) is in a perfect agreement with the prediction of the Fireball model.

36. GRB971214 @z=3.42

37. GRB N H and A V

38. HETE2 Fregate: 6-400 keV GRB triggers and low res. Spectra WXM 2-25 keV, medium energy resolution and 10arcmin localization SXC 0.5-10 keV, good energy resolution and 1arcmin localization

39. Swift: a new era for GRB studied Burst Alert Telescope (BAT) - 32,000 CdZnTe detectors - 2 sr field of view X-Ray Telescope (XRT) - CCD spectroscopy - Arcsec GRB positions UV-Optical Telescope (UVOT) - Sub-arcsec position - 22 mag sensitivity Spacecraft slews XRT & UVOT to GRB in <100 s

40. Swift GRBs XRF Short GRB XRF Short GRB XRF Short GRB XRF Short GRB Short GRB Short GRB Short GRB XRF Short GRB Short GRB

41. Swift localizes short GRBs elliptical hosts low SF rates offset positions redshifts z ~ 0.2 >> inconsistent with collapsar model >> supportive of NS-NS model BAT XRT Chandra

42. Il GRB piu’ lontano, quello piu’ brillante e quello piu’ energetico GRB080319B GRB080913 GRB080916C Fermi  -rays

43. 3 GRB @ z>6 Subaru Spectroscopy GRB050904 Ly break in the IR J=17.6 at 3.5 hours

44. Observational Constraints on the Central Engine Host Galaxies GRB Environments Prompt Emission Bumps in the Afterglow (SN?) Energetics and Beaming Using GRBs as Cosmological Probes

45. I: Host Galaxies The fading optical afterglow of GRB 990123 as seen by HST on Days 16, 59 and 380 after the burst. Accurate positions Allowed Astronomers To watch the bursts Fade, and then Study their Host Galaxy ! Host Galaxy Optical Afterglow

46. Properties Of Host Galaxies I) Like Many Star-forming Galaxies At that Observed redshift Holland 2001 II) Star-formation rates high, but consistent With star forming galaxies.

47. Location, Location, Location (In addition to detecting hosts, we can determine where a burst occurs with respect to the host.

48. GRB hosts GRBs trace brightest regions in hosts Hosts are sub-luminous irregular galaxies  Concentrated in regions of most massive stars  Restricted to low metallicity galaxies

49. If we take These Positions At face Value, We can Determine The Distribution Of bursts With respect To the half- Light radius Of host Galaxies! This Will Constrain The models! Distribution Follows Stellar Distribution

50. GRB Hosts Exhibit Larger Mg line Equivalent Widths Than QSO absorbers: Higher Density? Fiore 2000 Salamanca et al. 2002 Savaglio, Fall & Fiore 2003

51. Results from low resolution spectroscopy Savaglio, Fall & Fiore 2003 High dust depletion High dust content Denser clouds

52. 2) Metallicity depends on galaxy mass Savaglio et al. 2008 Berger et al. 2006

53. Star-formation rate in GRB hosts Savaglio+ 2008

54. What we’ve learned from GRB Hosts! Hosts of long GRBs are star-forming galaxies GRBs trace the stellar distribution (in distance from galaxy center) GRBs occur in dense environments (star forming regions?)

55. Using GRBs as Cosmological Probes Gamma-Ray Bursts are observed at extremely high redshifts and can be used to study the early universe. Star Formation History Beacons to direct large telescopes to study nascent galaxies Studies of intervening material between us and GRB – akin to quasar absorption studies

56. METAL ABUNDANCES IN HIGH z GALAXIES GRB explosion site Circumburst environment To Earth Host gas far away

57. Redshift Distribution Of GRBs With known Redshifts (2002) Redshifts As high as 5 observed! Lloyd-Ronning et al. 2002

58. Solid squares Denote bursts With observed Redshifts. Open squares Denote Positions using A Luminosity- Variability Relation. (Fenimore & Ramirez-Ruiz 2000). Dashed line Artifact of Luminosity Cut-off in FR-R Sample. Lloyd-Ronning, Fryer, & Ramirez-Ruiz 2002

59. Redshift distributions Redshift (z) Pre-Swift Swift Galaxies Quasars GRBs 10 12 13 8 Distance (Billion Light Years) 0 1 2 4 10

60. High resolution spectroscopy: GRB021004 FORS1 R~1000 CIV CIV z=2.296 z=2.328 UVES R=40000 z=2.296 z=2.328

61. GRB050730 UVES spectrum

62. GRBs show higher gas densities and metallicities, And have significantly lower [(Si,Fe,Cr)/Zn] ratios, Implying a higher dust content: Star Formation Region GRB locations within galaxies

63. History of metal enrichment Savaglio+2003 Prochaska+ 2003 050730 030323 000926 050820 050401 060206 050904

64. GRB host galaxy metallicities However… metallicity depends on: 1)Impact factor 2)Galaxy mass 3)Star-formation rate 4)Etc….

65. 1) Metallicity depend on impact factor GRB021004

66. Variability GRB060418 z=1.49 VLT/UVES Vreeswijk et al. 2007

67. Intervening absorbers Ly  forest: deviation from what is already known from quasar forests. ``Proximity effect'' should be much reduced for GRBs. An accurate determination of dn/dz at high z has strong implications for investigations of the re-ionization epoch, since the optical depth due to Ly  line blanketing is evaluated by extrapolating the Ly  dn/dz measured at lower-z. MgII and CIV absorbers: Incidence of MgII absorbers ~4 times higher than along QSO sight-lines. Incidence of CIV absorbers similar… WHY???

68. Dust composition/evolution the case of GRB 050904 @z=6.3 Large X-ray absorption and UV dust extinction Haislip WFCAM- UKIRT ~0.5 days, Ly  corr. = 3.02 Tagliaferri FORS- VLT ~1 day, Ly  corr. = 1.27 Haislip GMOS- Gemini ~3 days, Ly  corr. = 2.38

69. GRB 050904 z=6.3 Stratta et al 2007 QSO@6.2 extinction curve 0.5 day A 3000 =0.89+\-0.16 1 day A 3000 =1.33+\-0.29 3 days A 3000 =0.46+\-0.28 N H ~10 23 cm -2  A V /N H ~50 times lower than Galactic!! @z~6 no dust from AGB stars. Only sources are CCSNe (and AGNs) Much less dust and much smaller A V /N H

70. GRB Environments II: Studying the environment using radio and optical observation of GRBs Density profiles are different for different environments: massive stars will be enveloped by a wind profile. These different density profiles produce different radio, optical emission.

71. The Density Profile from Winds

72. ISM density is constant The Shock Radius Depends On the Density Profile! Radio And Optical Light Curves Are a Function Of this Radius!

73. For Many Gamma-Ray Bursts, Wind-swept Environments Best fit the Data (radio And R-band Data best Diagnostics! Li & Chevalier 2003 Roger Chevalier GRB021004

74. On the Surface, It appears we Can constrain The environments, But, beware, There still remain Many free Parameters in These calculations!

75. The connection between SNe and GRBs

78. Afterglow and GRB Energetics IV: As we learned yesterday, afterglows allowed us to calculate redshifts. Assuming a cosmology, we can then get distances. Assuming isotropic explosions, we can estimate the GRB energies! These energies range over many orders of magnitude.

79. GRBRedshiftIsotropic Energy GRB9702280.6955 x 10 51 GRB9705080.8358 x 10 51 GRB9708280.958NA GRB9712143.4183 x 10 53 GRB9803261?3 x 10 51 GRB9803292 or 3-5NA GRB9804250.008510 48 GRB9806131.096NA GRB9807030.9661 x 10 53 GRB9901231.6003 x 10 54 GRB Redshifts (2000) GRBRedshiftIsotropic Energy GRB990308>1.2?NA GRB9905061.3NA GRB9905101.6193 x 10 53 GRB9907050.86NA GRB9907120.430NA GRB9912080.7061.3 x 10 53 GRB9912161.026.7 x 10 53 GRB0001314.510 54 GRB0004181.1185 x 10 52 GRB0009262.0662.6 x 10 53

80. Afterglow and GRB Energetics As we learned yesterday, afterglows allowed us to calculate redshifts. Assuming a cosmology, we can then get distances. Assuming isotropic explosions, we can estimate the GRB energies! These energies range over many orders of magnitude. But are GRBs isotropic?

81. Jet Signatures GRB 010222 Stanek et al. (2001) Piran, Science, 08 Feb 2002

82. Energy and Beaming Corrections The dispersion in isotropic GRG energies results from a variation in the opening (or viewing) angle The mean opening angle is about 4 degrees (i.e.  f b -1  ~ 500 ) Geometry-corrected energies are narrowly clustered (1  =2x) Frail et al. (2001) 15 events with z and t_jet

83. Energy and Beaming (Continued) Improved analysis Larger sample Used measured densities Error propagation Geometrically corrected gamma-ray energy … Increase is due to using real density values 1  of 0.35 dex (2.2x) Bloom, Frail & Kulkarni (2003) 24 events with z and t_jet Outliers

84. Summary of GRB Energetics Gamma-ray bursts and their afterglows have (roughly) standard energies Robust result using several complementary methods E   gamma-rays E k  X-rays E k  BB modeling E k  Calorimetry

85. SN/GRB connection! GRBs have SN-like outbursts. But these bursts are beamed, and we won’t see all explosions as a GRB. What do we make of the SN/GRB connection: I)All GRBs produce SNe? II)All SNe are GRBs (only those observed along the jet axis are GRBs)? Are either of these true?

86. Ambitious Theorists – New SN Mechanism Collapsar Theorists argue I) is true, but not II) Others argue that all supernovae have jets (e.g. asymmetries in SN1987A) and the standard SN engine is wrong! SN-like is NOT SN

87. What fraction of SNe are GRBs? The GRB community tends to not talk to the SN community. Hence this problem has lingered for a long time. The simple fact is that the SN-like spectra and lightcurves are quite different than true SNe. But let’s assume we don’t know this, how else can we tell? - Radio!

88. A Complete Radio Catalog 5 yr period (1997-2001) BeppoSAX, IPN, RXTE and HETE satellites 75 GRBs searched for radio AGs searches at 5 and 8.5 GHz frequencies 0.8-650 GHz 1521 flux density measurements (or limits) 2002-2003 data on Web Frail, Kulkarni, Berger and Wieringa AJ May 2003 http://www.aoc.nrao.edu/~dfrail/grb_public.shtml

89. Cumulative Flux Density Distribution Max radio flux 2 mJy 19 detections –mean=315+/-82 uJy 44 GRB in total –mean = 186+/-40 uJy 50% of all bursts are brighter than 110 uJy Radio afterglow observations are severely sensitivity limited! Complete sample of 44 GRBs with 8.5 GHz measurements made between 5 and 10 days post-burst 50 %

90. Spectral Radio Luminosity Complete sample of 18 GRBs with redshifts and 8.5 GHz measurements made between 5 and 10 days post-burst

91. Fireball Calorimetry Long-lived radio afterglow makes a transition to NR expansion –no geometric uncertainties –can employ robust Sedov formulation for dynamics –compare with equipartition Most energy estimates require knowledge of the geometry of the outflow –radius and cross check with ISS-derived radius Limited by small numbers Frail, Waxman & Kulkarni (2000)

92. How Common are Engine- Powered SNe? VLA/ATCA survey of 34 Type Ib/c SNe to detect off-axis GRBs via radio emission Berger PhD Most nearby SNe Ib/c do not have relativistic ejecta Two distinct populations E k (GRB)<<1 foe (hydo collapse) <10% are 1998bw-like